What do you need to start?
Use nine squares arranged in three rows and three columns. One player uses X and the other O. A pencil and paper work, or you can share a phone and tap squares in our game.
On paper, agree who starts. X is a common choice, but the symbols themselves do not change the rules. Our examples use X as the first player; our app can change the starter between rounds.
What can you do on your turn?
- Choose one empty square. Place your own mark there. You cannot take an occupied square or replace the other player’s mark.
- Leave existing marks in place. In ordinary 3×3 Tic-Tac-Toe, pieces do not move after placement. There is no capture or sliding phase.
- Hand over the turn. After one valid placement, the other player chooses an empty square. Continue until a win or draw ends the round.
Which lines count as a win?
Three matching marks win across any row, down any column or along either corner-to-corner diagonal. There are eight possible winning lines: three rows, three columns and two diagonals.
The marks must form a straight line. Three Xs scattered across different rows do not count. An L-shape does not count either.
For example, X in the top-left, centre and bottom-right squares wins on a diagonal. The round ends as soon as that third X is placed, even if other squares are still empty.
When is a game a draw?
A completed board with no winning line is a draw. Nobody has to remove a mark or keep playing beyond the ninth placement. If the last move completes a winning line, that is a win rather than a draw.
A draw is also the result both players can secure with perfect play from an empty board. Going first does not guarantee a win, and going second does not mean you must lose.
How do two people play on one phone?
Open Tic-Tac-Toe and choose the friend / two-player mode in the lobby. Both players use the same board, taking turns rather than tapping simultaneously. Follow the X or O turn indicator.
In PaperFox’s friend mode, the loser starts the next round. After a draw, the starter switches. Against the computer, the first move alternates between rounds. These are our rematch rules, not a requirement for every paper game.
Browser play needs a connection to load. In either of our installed Android game collections, local two-player Tic-Tac-Toe works without pairing two phones or connecting to wifi.
What changes between computer levels?
The board and winning rules stay the same. Easy makes mistakes. Medium takes immediate wins and blocks immediate threats, but can miss longer plans. Hard looks ahead and cannot be beaten from the normal starting position if it keeps playing perfectly.
Learn the rules against Easy first. When you want to improve your decisions, our Tic-Tac-Toe strategy guide explains blocking and forks with worked positions.
Questions
- Can you win diagonally? Yes. Either complete diagonal of three matching marks counts, as do the three rows and three columns.
- Can you move an X or O after placing it? Not in the standard 3×3 game described here. You add one mark to an empty square on your turn and leave earlier marks in place.
- Does X always have to start? Many games use that convention, but players can agree otherwise. Our app changes the starter between rounds using the rematch rules above.
